Technical Field
The present invention relates to a circuit substrate having a built-in component used in a high frequency communication module or the like.
Background Art
A conventional configuration of a circuit substrate having a built-in component used in high frequency communication modules or the like includes stacking insulating layers and conductive layers together and having a metal core layer that is a conductive layer thicker than the other conductive layers and that functions as ground. Various types of electronic components such as duplexers, filters, and the like are arranged in penetrating holes formed in this core layer (see Patent Document 1). In this type of conventional circuit substrate having a built-in component, the core layer is located inside the circuit substrate, and insulating layers and conductive layers are stacked on both the top and bottom of the core layer. A signal wiring line for transmitting high frequency signals is formed in one of the conductive layers facing this core layer. This type of circuit substrate having a built-in component is advantageous due to the core layer ensuring the strength of the circuit substrate and shielding the built-in electronic components.